Air traffic control systems and procedures are designed to reduce the likelihood that aircraft will collide with each other or with objects on the ground. To this end, air traffic controllers (ATC) typically assign specific flight paths to aircraft which, if adhered to, are designed to keep individual aircraft in their own lanes. These paths may be constant altitude paths, or the paths may be assigned paths (e.g., three dimensional directions from one point in space to another point in space, including level paths, ascending paths and descending paths).
During a typical flight, an aircraft may be assigned to a new altitude, and may begin an ascent or descent to that altitude. The aircraft achieves the assigned altitude once it is steadily flying at the new assigned altitude. At some point before the aircraft achieves the assigned altitude, an adjustment to the pitch and thrust is typically made to effect a smooth transition from the ascent/descent maneuver to the constant altitude portion of the flight. Initiating the adjustment(s) to the pitch and thrust is known as initiating the “capture” of the assigned altitude. If capture of the assigned altitude is delayed, the aircraft may either overshoot the assigned altitude or perform a rough transition to the constant altitude portion of the flight. Either of these conditions may potentially create an unsafe condition as the aircraft could enter into airspace for which it has not received ATC clearance. An overshoot of the assigned altitude by greater than, for example, 250 feet, is known as a “bust” or “altitude bust” and is a violation of Federal Aviation Administration rules.
During a maneuver to an assigned altitude or vertical path, a pilot typically receives feedback regarding the altitude, thrust, heading, rate of ascent, and other information from a primary flight display panel. Modern day flight display panels are typically electronic, as opposed to analog indicators such as dials and gauges. These electronic displays may be, for example, flat screens or computer monitors. In particular, the display screens often show an altitude tape indicating the current altitude and another indicator on the screen may show the rate of ascent or descent. However, these indicators do not typically display information regarding when capture of the assigned altitude should begin, the path that should be taken to acquire the assigned altitude, or the last point to begin capture without an altitude bust.
Often, aircraft are equipped with flight management systems, auto pilots, and other automated flight control systems. These systems typically control the aircraft to relieve the pilot of repetitive tasks such as instantaneous aircraft trajectory control. Moreover, the automation is also typically capable of performing these tasks consistently with better accuracy than manual pilot operation. A pilot typically conveys the assigned altitude or assigned path to the automation (e.g., auto pilot) via a mode control panel, a multi-function control and display unit (MCDU), or like electronic systems. The automation then typically controls the aircraft's pitch and thrust to achieve the pilot's instructions. Alternatively, the pilot may manually control the aircraft's pitch and thrust to fly the plane along an assigned path.
An aircraft guided by automatic pilot typically accurately processes the many changing variables such as wind speed, thrust, pitch, positioning of control surfaces, and weight of the aircraft to determine and follow a path which smoothly transitions from the ascent/descent phase to the level flight phase or, in general, from one phase to another phase. Performing this same task under manual control is difficult because no “rules of thumb” or bright line tests are available to assist the pilot in accounting for all of these factors. Aircraft pilots often closely monitor the performance of the auto pilot and are prepared to make corrections if necessary. It is important, therefore, that the pilot is provided accurate and timely information allowing the pilot to make informed decisions, make more efficient use of the automation, and make fewer pilot errors.
When an aircraft experiences an altitude bust by overshooting a target altitude by, for example, 250 feet, the incident must typically be reported to the FAA or other regulatory body. Several recent Safety Reports (e.g., NTSB-A-99-39 to -44, 1999) and Aviation Safety Reporting System (“ASRS”) Reports indicated that a contributing factor to described incidents and accidents was the pilot's lack of knowledge of the trajectory used by the auto-pilot to capture the assigned altitude. Several researchers have also identified situations in which the pilots were not aware of the capture trajectory commanded by the automation.
The continued advancement in the sophistication of aircraft flight displays has resulted in increasingly higher levels of information density which has presented a greater amount of visual information to be perceived and understood by the aircraft operator. In many applications, it is important that visual displays provide a proper cognitive mapping between what the operator is trying to achieve and the information available to accomplish the task. As a result, such systems increasingly utilize the human-factor design principles in order to build instrumentation and controls that work cooperatively with human operators. More particularly, Title 14 of the U.S. Code of Federal Regulations, Federal Aviation Regulations (FAR) Part 25, Sec. 25.1321 et seq. provides guidelines for the arrangement and visibility of instruments, warning lights, indicators, and the like. Similarly, detailed guidelines related to electronics displays can be found in FAA Advisory circular 20-88A, Guidelines on the Marking of Aircraft Powerplant Instruments (September 1985). Both of these documents are incorporated herein by reference in their entirety as background information.
Current display information may be improved to assist pilots in determining when capture initiation should begin. Therefore, a need exists for a method and apparatus to display FMS (“Flight Management System”), auto pilot, and other flight control system calculated capture initiation information to a pilot to reduce pilot errors.